The contingency theory is a leadership theory developed by Fred Fiedler. He believes that leadership effectiveness depends on both the leader's personality and the situation. Certain leaders are effective in one situation but not in others, and it's therefore a situational theory in the meaning that there is no one best way of leading.

Fiedler uses three devices to determine the leader personality and the situation:

Least Preferred Coworker (LPC) Scale

Situational Favorableness

Leader-Situation Match and Mismatch

Although this theory has its shortcomings (for instance it excludes training and experience as variables) it's the first and perhaps most popular situational theory to date.